Abstract: A method and system for capturing images. First, a preview image of a scene is captured. Next, an automatic determination is made whether the scene is a document. When it is determined that the scene is a document, at least one camera control is set to a value that is tailored for document capture. The scene is then captured using the set camera controls. Image processing that is tailored for documents is then performed on the captured scene.

Abstract: An apparatus and method for dither matrix design for color halftoning using dispersed dot clusters where the dot cluster centers are arranged in a homogeneous and isotropic pattern, in order avoid the moiré effect. The method requires that the size of the array and the number of dot seeds that will be in the array be predetermined.

Abstract: An image enhancement apparatus and a corresponding method use face detection to provide for automatic enhancement of appearances of an image based on knowledge of human faces in the image. By modifying and transforming the image automatically using facial information, the image, including the human faces in the image, may have more pleasing lightness, contrast, and/or color levels. The image enhancement method may also automatically reduce or remove any red eye artifact without human intervention, leading to images with more pleasing appearances.

Abstract: A method and system for halftoning images that uses error diffusion with partial dots is provided. First, an input picture element (input pixel) that has a picture level (e.g., gray level) is received. Next, a reproducible gray level is generated based on the gray level of an input pixel. Then, a corrected gray level is generated based on the gray level of an input pixel and an error amount (e.g., error propagated or diffused from adjacent areas or pixels). A determination is made whether the corrected gray level is in a predetermined relationship with a threshold. When the corrected gray level is in a predetermined relationship with the threshold, the reproducible gray level (i.e., partial dot size) is provided as output. When the corrected gray level is not in a predetermined relationship with the threshold, a zero value is provided as output.

Abstract: A color image is converted into a dot pattern for display by a color printer. The image is separated into Cyan, Magenta and Yellow color planes; a dither matrix is applied to the Cyan plane; an inverse of the dither matrix is applied to the Magenta plane; and either the dither matrix or the inverse dither matrix is applied to the Yellow plane.

Abstract: A method of generating a halftone image from a gray scale image using stochastic halftoning printing screens. A clustered dot stochastic screen is prepared for multiple gray levels by using a first filter at the lightest gray levels, switching to a donut filter at gray levels after a selected transition level, optionally using the donut filter at all gray levels. The donut filter has its maxima away from the current pixel.

Abstract: A pixel color in an image can be represented by a dot color in a dot pattern as follows. A subset of a limited set of display colors is selected. The subset has N display colors that can render a solid color patch of the pixel color. The colors of the subset correspond to vertices of a simplex in the color space. The simplex has (N−1) dimensions. A point operation is then performed to select one of the vertices of the simplex and thereby select the dot color of the subset color corresponding to the selected vertex. Consequently, a solid patch of the pixel color can be rendered by a dot pattern having no more than N different colors. The dot pattern can be displayed by an imaging device such as an inkjet printer, which has a limited set of display colors.

Abstract: A process and apparatus is described to improve the digital processing of scanned negative films by reducing the amount of time necessary to perform the process and by increasing the robustness and quality of the images produced. These benefits are achieved by a process of color inversion, white point and black point mapping, and midtone adjustment. White and black mapping increases the dynamic range of the image, as well as removes the color cast of the negative film. A backlit image postprocessing algorithm can be employed which uses heuristics to identify backlighted situations, which are then brightened using a nonlinear power mapping. A midtone adjustment can include the sub-steps of contrast reduction and color adjustment. Contrast reduction reverses the film exposure characteristics. Color adjustment removes the remaining color cast in the midtone region of the image, and obtains the correct brightness.

Abstract: An Adaptive Image Resolution Enhancement Technology (IRET) process and apparatus is described to improve halftone imaging by changing ordered halftone screen resolution according to the content of the image and managing these changes based on image content. The Adaptive IRET halftoning technique maximizes the artifact reducing properties of coarser ordered screens, while minimizing the loss of rendered detail in image areas having high spatial frequency. IRET may utilize a mixture of any ordered halftone screen (e.g. clustered-dot dither, line screen, etc.) to generate halftone dots with a number of levels, and any dispersed halftone screen to generate additional levels for the ordered halftone dots. For some printing technologies, it is preferable to minimize printing artifacts by generating coarser halftone screens, rather than finer halftone screens. Coarser screening, however, means that details in the image, text, and line art will not be rendered well.

Abstract: A red-eye reduction system is described that includes a masking module. The masking module converts an image into a mask having first state areas representing red color pixels of the image and second state areas representing other color pixels of the image. The image includes an eye with a red pupil. A pupil locating module is coupled to the masking module to locate a substantially first state area in the mask that resembles a pupil. A color replacing module is then coupled to the pupil locating module to change the red color pixels in the area into monochrome (grey) or other predefined colors. The color replacing module also adjusts the boundary of the area by changing the colors of pixels in close proximity to the area if the color of these pixels is determined to be sufficiently close to red such that natural appearance of the eye is maintained when reducing the red pupil. A method of reducing red-eye effect in a digital image is also described.

Abstract: Various patterns, such as those derived from halftoning techniques, are applied to the design of print masks for inkjet printers to improve print quality. Print masks are used to control the firing sequence of the nozzles in a print head in multiple pass printing mode and thereby determine the nozzles that are to print in each particular media location. Such techniques as halftoning techniques have been used to print gray scale images with bi-level printing to produce bi-level patterns that can be perceived as gray density by human eyes from a viewing distance. State-of-the-art print masks typically provide checkerboard patterns that are not sufficient to handle severe print artifacts. A novel triangular clustering print mask that may be derived from halftoning techniques is applied to produce an imperceptible printed pattern that covers up the banding artifacts caused by defective print head nozzles.

Abstract: A process and apparatus is described to improve halftone image quality by integrating different halftoning algorithms and managing their transitions based on image content. The method works by applying different halftoning methods to different regions of a continuous-tone image. Regions of the continuous-tone image are evaluated to determine suitability for halftoning by at least two different halftoning methods. The most suitable halftoning method is then used to halftone a particular region. An activity index is used to evaluate each region. A halftoning method such as error diffusion is deemed most suitable for application to detailed continuous-tone image areas. A halftoning method such as smooth dither is deemed most suitable for application to flat continuous-tone image areas . Also, hysteresis can be introduced to compensate for sharp transitions in the image and thereby eliminate ghosting.

Abstract: A process and apparatus improve color halftone imaging for ink-based printing by reducing the amount of time necessary to perform the halftoning process, by reducing the amount of ink consumed and by increasing the quality of the images produced. These benefits are achieved by adapting Image Resolution Enhancement Technology (IRET) to render color images that achieve near-photographic image quality on a color inkjet printer having multiple dye load and increased scan axis addressability, while keeping the computation complexity to a minimum. This is achieved by designing basic patterns at multiple intensities, and by using a multi-level halftoning technique to obtain smooth gradations. For plain paper, as well as for coated paper, multi-level halftoning is performed on an asymmetric geometry to yield the best result, while for glossy paper, a regular geometry yields the best result because of the limited ink absorption capacity for glossy paper.

Abstract: A print apparatus performs a halftoning action on a raster pixel image. The print apparatus includes a super-pixel data base for storing plural n.times.n superpixels, each superpixel corresponding to a subset (or "bucket") of gray level pixel values. The method comprises the steps of: logically tiling a dither matrix across the raster pixel image and outputting a threshold value which, logically and positionally corresponds to a given image pixel value. The given image pixel value is then quantized into a selected bucket of pixel values which encompass the given image pixel value. A proportionality value is then determined which identifies the relative position of the given image pixel value within the selected bucket of pixel values. The outputted threshold value is then compared to the determined proportionality value, and the selected bucket number is incremented to a next sequential bucket number if the proportionality value exceeds the threshold value.

Abstract: A digital color processing method for images from scanners and digital cameras processes image data suitable for display on monitors or color hardcopies produced by digital color printers and correct hue shift and incorrect exposure based on the image content. The method automatically corrects the data based on the histogram of the acquired image normalizing the image data to correct for the hue shift and determining the gamma parameter to correct the exposure of the image.

Abstract: The present invention provides a system and method for generating halftone patterns. Typically the generated halftone patterns are used for generating dither matrices to halftone a image with improved visual quality. The steps for generating a plurality of color halftone patterns include: defining a color path from a color concentration level p to a color concentration level q; and generating a halftone patterns f.sub.j for each color concentration level j along the defined color path. After the halftone pattern f.sub.j is generated for the color concentration level j, the color fluctuation of the halftone pattern f.sub.j is minimized. A key contribution of the current invention is the decomposition of a color halftone pattern which occurs during the step of minimizing the color fluctuation for halftone pattern f.sub.j, and which allows simultaneous optimization of underlying color halftone patterns. After the step of minimizing the halftone pattern f.sub.

Abstract: A method and a system for generating a dither matrix calibrated to a desired tonal response. The method and system comprise generating a dither matrix with a predicted tonal response, measuring the actual tonal response, manipulating a cumulative histogram for the dither matrix in response to the actual tonal response, and inputting the cumulative histogram to a dither matrix generation program to generate a dither matrix that conforms to the cumulative histogram. Other systems and methods are disclosed.

Abstract: Methods and apparatus generate, and use in printing, a dither matrix that incorporates a vivid-response function, that follows a generally S-shaped response curve. Printing with this pregenerated dither cell is just as fast as with a conventional cell, but printed color has a slightly exaggerated vividness, more pleasing to most users than more-accurately reproduced color. Color printed with this curve alone, however, is found unsatisfactorily dark; the invention also encompasses including in the overall response another function to lighten the colors--particularly at the low end of the brightness range. We define both functions as so-called "gamma functions", but with different arguments and exponents, and construct the S-shaped curve as two separate sections blended at a generally central point. Preferably the argument of the first (low-brightness) section is an expression that is proportional to an input color signal; the function raises this argument to a power greater than unity (ideally 1.6).

Abstract: Generating a N-tone image from a grey scale image with a number of multi-level dither matrices. Both images have many pixels, with each pixel in the grey scale image having a grey level that is within a maximum and a minimum levels, and with each pixel in the N-tone image having a level that is one of N levels with N bigger than two. The method includes the step of determining the level of each pixel in the N-tone image based on the levels of its corresponding pixel in the grey scale image, and an original dither matrix, the separations between adjacent levels in the N levels are not uniform. After the determination process, every pixel in the N-tone image is modelled to represent its level. Based on the modelling, the N-tone image is printed.

Abstract: Generating a N-tone image relatively inexpensively with substantially imperceptible dots. The method generates the N-tone image from a grey scale image, both images have many pixels, with each pixel in the grey scale image having a grey level that is within a maximum and a minimum level, and with each pixel in the N-tone image having a level that is one of N levels with N bigger than two and less than the number of levels available for the grey scale image. The method includes the steps of determining the level of each pixel in the N-tone image based on the levels of its corresponding pixel in the grey scale image, and based on either an original dither matrix or an error diffusion technique. Each pixel is modelled by a number of sub-pixels, and each sub-pixel is modelled by a number of segments. Each segment has an intensity whose value depends on its corresponding pixel. The different intensities of the segments when combined together generate N substantially reproducible levels for the N-tone image.